CI Atlas · When Things Go Wrong: Complications and Troubleshooting · Module 10

10The Poor Performer: A Structured Workup

Some recipients never reach the scores their candidacy predicted; others slip backwards after years of stable hearing. Both are 'poor performers,' and both deserve the same discipline: a structured, stepwise differential that interrogates the device, the cochlea, the map, and the brain before anyone reaches for the word 'soft failure.'

CTwo clinical pictures, one differential

Distinguish the never-good performer (open-set scores persistently below the range expected for the candidacy profile) from the decliner (a documented fall from a previously stable plateau, with or without aversive symptoms such as popping, buzzing, or shocking). A documented decline after good initial performance points more strongly to a device, electrode, or cochlear cause than the never-good picture, where biological, cognitive, and central factors dominate. Aversive non-auditory symptoms (facial twitch, dizziness, pain on stimulation) reframe the workup toward electrode position and current spread rather than a pure programming question. Anchor every workup to objective baselines from activation: a 'change' only has meaning against a recorded prior state, so longitudinal impedance, ECAP, map, and word-score data are the most valuable item in the chart.[2016][2010][2005]

Start with the cheapest, most common fault: history, datalogging and a swap of the external processor, coil and cable. A failing microphone or low wear time explains many sudden drops before anything internal is suspected. The algorithm escalates from cheap and external to expensive and internal: Step 1 externals → Step 2 impedance and integrity test → Step 3 ECAP and remap → Step 4 imaging. Working in this order finds the common, reversible causes first and reserves CT for the cases the device and the map cannot explain. Schematic.

CThe differential, organized by layer

Device/hardware: hard failure of the receiver-stimulator, intermittent internal fault, processor/coil/cable problems, microphone or magnet issues are the most reversible and should be excluded first. Electrode/cochlea: tip fold-over, scalar translocation, partial insertion, migration or extrusion, and new intracochlear ossification or fibrosis each degrade the neural interface in a localizable way. Programming/map: drifted T/C levels, deactivated channels never reinstated, inappropriate strategy or rate, pitch reversals, and uncorrected impedance changes can masquerade as device failure. Host/central: progressive loss of residual acoustic hearing in an EAS user, retrocochlear or central pathology, declining cognition, depression, intercurrent illness, and simple non-use or unrealistic expectations round out the differential.[2016][2009][2010]

CThe stepwise algorithm

Step 1 history and externals: timeline of the change, symptom diary, datalogging/usage hours, and a swap of every external part (processor, coil, cable, battery) to exclude the cheap fixes. Step 2 device interrogation: confirm lock and telemetry, then run impedance across the array and the manufacturer integrity test to separate a hardware fault from a biological one. Step 3 electrophysiology and behaviour: ECAP/telemetry and field measures, then a careful remap with fresh impedances, channel-by-channel pitch and loudness review, and repeat validated speech testing in quiet and noise. Step 4 imaging: radiograph or flat-panel/cone-beam CT when position is suspect, with audiology and host factors reassessed in parallel rather than serially.[2010][2004][2001]

TSoft failure as a diagnosis of exclusion

The consensus definition of soft failure is a suspected device malfunction that cannot be proven by currently available in vivo methods; by construction it is only reached after the structured workup is negative. In revision series, the majority of suspected soft failures presented with aversive symptoms or performance decline while the device still maintained a lock and passed integrity testing. Labelling a case 'soft failure' carries weight: it justifies revision surgery, so the workup must genuinely exclude reversible map, electrode-position, residual-hearing, and host causes first. Standardized reliability/failure terminology (the international classification) keeps reporting honest and lets centres compare device-attributable decline against patient-attributable variability.[2005][2010][2010]

Case 25.10 · The Poor Performer

A 58-year-old, 4 years post-implant, had stable CNC word scores around 70% for 3 years. Over 6 weeks her scores fell to 35% and she reports intermittent 'popping.' External parts have been swapped with no change. The device still locks and the integrity test is normal.

What is the single best next step?

Self-assessment — Module 103 questions

Question 1

Which presentation most strongly suggests a device or electrode cause rather than a host/central one?

Question 2

By consensus definition, a cochlear implant 'soft failure' is:

Question 3

Which is the correct first step in a structured poor-performer workup?

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